Process for xylene and ethylbenzene isomerization using UZM-35HS

ABSTRACT

Xylene and ethylbenzene isomerization process is catalyzed by the UZM-35 family of crystalline aluminosilicate zeolites represented by the empirical formula:
 
M m   n+ R r   + Al (1-x) E x Si y O z  
 
where M represents a combination of potassium and sodium exchangeable cations, R is a singly charged organoammonium cation such as the dimethyldipropylammonium cation and E is a framework element such as gallium. These UZM-35 zeolites are active and selective in the isomerization of xylenes and ethylbenzene.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation-In-Part of co-pending applicationSer. No. 12/751,720 filed Mar. 31, 2010, the contents of which arehereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to the use of zeolite UZM-35 in a processof isomerizing xylenes and ethylbenzene. The zeolite UZM-35 may bepresent in the catalyst as unmodified zeolite UZM-35 or as UZM-35modified zeolite. The UZM-35 containing catalyst may take one of severalforms, including for example a spherical oil-dropped catalyst or anextruded catalyst.

BACKGROUND OF THE INVENTION

Zeolites are crystalline aluminosilicate compositions which aremicroporous and which have a three-dimensional oxide framework formedfrom corner sharing AlO₂ and SiO₂ tetrahedra. Numerous zeolites, bothnaturally occurring and synthetically prepared, are used in variousindustrial processes. Synthetic zeolites are prepared via hydrothermalsynthesis employing suitable sources of Si, Al and structure directingagents such as alkali metals, alkaline earth metals, amines, ororganoammonium cations. The structure directing agents reside in thepores of the zeolite and are largely responsible for the particularstructure that is ultimately formed. These species balance the frameworkcharge associated with aluminum and can also serve as space fillers.Zeolites are characterized by having pore openings of uniformdimensions, having a significant ion exchange capacity, and beingcapable of reversibly desorbing an adsorbed phase which is dispersedthroughout the internal voids of the crystal without significantlydisplacing any atoms which make up the permanent zeolite crystalstructure. Topological zeolite structures are described in Atlas ofZeolite Framework Types, which is maintained by the InternationalZeolite Association Structure Commission athttp://www.iza-structure.org/databases/. Zeolites can be used ascatalysts for hydrocarbon conversion reactions, which can take place onoutside surfaces as well as on internal surfaces within the pore.

Catalysts for isomerization of C₈ aromatics ordinarily are classified bythe manner of processing ethylbenzene associated with the xyleneisomers. Ethylbenzene is not easily isomerized to xylenes, but itnormally is converted in the isomerization unit because separation fromthe xylenes by superfractionation or adsorption is very expensive. Awidely used approach is to dealkylate ethylbenzene to form principallybenzene while isomerizing xylenes to a near-equilibrium mixture. Analternative approach is to react the ethylbenzene to form a xylenemixture via conversion to and reconversion from naphthenes in thepresence of a solid acid catalyst with a hydrogenation-dehydrogenationfunction. The former approach commonly results in higher ethylbenzeneconversion, thus lowering the quantity of recycle to the para-xylenerecovery unit and concomitant processing costs, but the latter approachenhances xylene yield by forming xylenes from ethylbenzene. A catalystcomposite and process which enhance conversion according to the latterapproach, i.e., achieve ethylbenzene isomerization to xylenes with highconversion, would effect significant improvements in xylene-productioneconomics.

Especially advantageous would be a commercially utilizable catalystcontaining 12-membered rings and 10-membered rings in the same3-dimensional structure. Commercial utility is typically seen inaluminosilicate structures which are synthesized in hydroxide media withreadily available structure directing agents. Zeolites which containboth 12-membered and 10-membered rings in 3-dimensional structuresbelong to the CON, DFO, IWR, IWW and MSE structure types. The synthesisof CIT-1, a zeolite of the CON structure type, is described in U.S. Pat.No. 5,512,267 and in J. Am. Chem. Soc. 1995, 117, 3766-79 as aborosilicate form. After synthesis, a subsequent step can be undertakento allow substitution of Al for B. The zeolites SSZ-26 and SSZ-33, alsoof the CON structure type are described in U.S. Pat. Nos. 4,910,006 and4,963,337 respectively. SSZ-33 is also described as a borosilicate. All3 members of the CON structure type use very complicated, difficult tosynthesize structure directing agents which make commercial utilizationdifficult. The known member of the DFO structure type is DAF-1 which isdescribed as an aluminophosphate in Chem. Commun. 1993, 633-35 and inChem. Mater. 1999, 11, 158-63. Zeolites from the IWR and IWW structuretypes are synthesized only in hydrofluoric acid containing synthesisroutes, making commercial utilization difficult.

One particular zeolite of the MSE structure type, designated MCM-68, wasdisclosed by Calabro et al. in 1999 (U.S. Pat. No. 6,049,018). Thispatent describes the synthesis of MCM-68 from dication directing agents,N,N,N′,N′-tetraalkylbicyclo[2.2.2]oct-7-ene-2R,3S:5R,6S-dipyrrolidiniumdication, andN,N,N′,N′-tetraalkylbicyclo[2.2.2]octane-2R,3S:5R,6S-dipyrrolidiniumdication. MCM-68 was found to have at least one channel system in whicheach channel is defined by a 12-membered ring of tetrahedrallycoordinated atoms and at least two further independent channel systemsin which each channel is defined by a 10-membered ring of tetrahedrallycoordinated atoms wherein the number of unique 10-membered ring channelsis twice the number of 12-membered ring channels, see US 2009/318696.

Applicants have successfully prepared a new family of materialsdesignated UZM-35. The topology of the materials is similar to thatobserved for MCM-68. The materials are prepared via the use of simple,commercially available structure directing agents, such asdimethyldipropylammonium hydroxide, in concert with small amounts of K⁺and Na⁺ together using the Charge Density Mismatch Approach to zeolitesynthesis as shown in U.S. Pat. No. 7,578,993.

The UZM-35 family of materials is able to provide and maintain highconversion during xylene and ethylbenzene isomerization reactions andminimize ring loss. This is believed to be due to its particular poregeometry and framework Si/Al ratio. The UZM-35 zeolite containssignificant amounts of Al in the tetrahedral framework, with the moleratio of Si/Al ranging from about 2 to about 12. The Al content in theframework is known to provide acid sites required for high activity inisomerization processes.

Due to the unique structure of UZM-35, catalysts made from UZM-35 areable to show an advantage of about 30 to about 40% in ring retentionover 12-membered ring channel MTW zeolite catalyst in proof of principletesting. Furthermore, a UZM-35 containing extrudate also shows adifferent distribution of aromatic by-products and unique characterduring initial line-out period as compared to MTW zeolite-containingextrudates. Specifically, the by-product yields diminish without anydecrease in xylene isomerization activity, suggesting fouling of sitesspecific to undesired reactions.

SUMMARY OF THE INVENTION

The present invention relates to a process of xylenes and ethylbenzeneisomerization using a catalyst of the aluminosilicate zeolitedesignation UZM-35. The process comprises contacting the xylenes andethylbenzene with the UZM-35 zeolite at isomerization conditions to givea catalytically isomerized product. Isomerization conditions typicallycomprise a temperature of about 100° to about 500° C., a pressure ofabout 10 kPa to about 5 MPa absolute, a liquid hourly space velocityfrom about 0.5 to 10 hr⁻¹ and a hydrogen-to-hydrocarbon mole ratio fromabout 0.5:1 to 10:1.

The UZM-35 is a microporous crystalline zeolite having athree-dimensional framework of at least AlO₂ and SiO₂ tetrahedral unitsand an empirical composition in the as synthesized and anhydrous basisexpressed by an empirical formula of:M_(m) ^(n+)R_(r) ⁺Al_((1-x))E_(x)Si_(y)O_(z)where M represents a combination of potassium and sodium exchangeablecations, “m” is the mole ratio of M to (Al+E) and varies from about 0.05to about 3, R is a singly charged organoammonium cation selected fromthe group consisting of dimethyldipropylammonium (DMDPA⁺),dimethyldiisopropylammonium (DMDIP⁺), choline, ethyltrimethylammonium(ETMA⁺), diethyldimethylammonium (DEDMA⁺), trimethylpropylammonium,trimethylbutylammonium, dimethyldiethanolammonium, tetraethylammonium(TEA⁺), tetrapropylammonium (TPA⁺), methyltripropylammonium, andmixtures thereof, “r” is the mole ratio of R to (Al+E) and has a valueof about 0.25 to about 2.0, E is an element selected from the groupconsisting of gallium, iron, boron and mixtures thereof, “x” is the molefraction of E and has a value from 0 to about 1.0, “y” is the mole ratioof Si to (Al+E) and varies from greater than 2 to about 12 and “z” isthe mole ratio of O to (Al+E) and has a value determined by theequation:z=(m+r+3+4·y)/2and is characterized in that it has the x-ray diffraction pattern havingat least the d-spacings and intensities set forth in Table A:

TABLE A 2θ d (Å) I/Io % 6.45-6.8  13.7-13  m 6.75-7.13 13.1-12.4 m-vs7.86-8.26 11.25-10.7  m 8.64-9.04 10.23-9.78  m  9.51-10.09  9.3-8.77m-vs 10.62-11.23 8.33-7.88 w-m  13.4-14.22 6.61-6.23 w-m 14.76-15.55 6-5.7 w 17.63-18.37 5.03-4.83 w 19.17-19.91 4.63-4.46 w-m 19.64-20.564.52-4.32 m 20.18-21.05  4.4-4.22 w-m  20.7-21.57 4.29-4.12 w-m21.36-22.28 4.16-3.99 vs 22.17-23.6  4.01-3.77 m-s 24.12-25.23 3.69-3.53w  25.6-26.94 3.48-3.31 m 26.37-27.79 3.38-3.21 m 27.02-28.42  3.3-3.14m 27.53-28.89 3.24-3.09 m  28.7-30.09 3.11-2.97 m 29.18-30.72 3.06-2.91w-m 30.19-31.73 2.96-2.82 m 30.83-32.2   2.9-2.78 w 32.81-34.222.73-2.62 w 35.63-36.99 2.52-2.43 w 41.03-42.86  2.2-2.11 w 44.18-45.832.05-1.98 w 44.87-46.57 2.02-1.95 w 46.07-47.35 1.97-1.92 w 48.97-50.421.86-1.81 wand is thermally stable up to a temperature of greater than 400° C. inone embodiment and 600° C. in another embodiment.

The crystalline microporous zeolite described above may be synthesizedby forming a reaction mixture containing reactive sources of M, R, Al,Si and optionally E and heating the reaction mixture at a temperature ofabout 150° C. to about 200° C., or about 165° C. to about 185° C., for atime sufficient to form the zeolite, the reaction mixture having acomposition expressed in terms of mole ratios of the oxides of:aM₂O:bR_(2/p)O:1-cAl₂O₃ :cE₂O₃ :dSiO₂ :eH₂Owhere “a” has a value of about 0.05 to about 1.25, “b” has a value ofabout 1.5 to about 40, “p” is the weighted average valance of R andvaries from 1 to about 2, “c” has a value of 0 to about 1.0, “d” has avalue of about 4 to about 40, “e” has a value of about 25 to about 4000.

In another embodiment, the invention relates to a process of xylenes andethylbenzene isomerization using a catalyst of the aluminosilicatezeolite designation UZM-35HS. The process comprises contacting thexylenes and ethylbenzene with the UZM-35 zeolite at isomerizationconditions to give a catalytically isomerized product. Isomerizationconditions typically comprise a temperature of about 100° to about 500°C., a pressure of about 10 kPa to about 5 MPa absolute, a liquid hourlyspace velocity from about 0.5 to 10 hr⁻¹ and a hydrogen-to-hydrocarbonmole ratio from about 0.5:1 to 10:1.

The process comprises contacting the hydrocarbon with the UZM-35HSzeolite at xylene and ethylbenzene isomerization conditions to give anisomerized product. The UZM-35HS is a microporous crystalline zeolitehaving a three-dimensional framework of at least AlO₂ and SiO₂tetrahedral units and an empirical composition on an anhydrous basisexpressed by an empirical formula of:M1_(a) ^(n+)Al_((1-x))E_(x)Si_(y′),O_(z′)where M1 is at least one exchangeable cation selected from the groupconsisting of alkali, alkaline earth metals, rare earth metals, ammoniumion, hydrogen ion and mixtures thereof, “a” is the mole ratio of M1 to(Al+E) and varies from about 0.05 to about 50, “n” is the weightedaverage valence of M1 and has a value of about +1 to about +3, E is anelement selected from the group consisting of gallium, iron, boron, andmixtures thereof, “x” is the mole fraction of E and varies from 0 to1.0, y′ is the mole ratio of Si to (Al+E) and varies from greater thanabout 4 to virtually pure silica and z′ is the mole ratio of O to (Al+E)and has a value determined by the equation:z′=(a·n+3+4·y′)/2and is characterized in that it has the x-ray diffraction pattern havingat least the d-spacings and intensities set forth in Table A:

TABLE A 2θ d (Å) I/Io % 6.45-6.8  13.7-13  m 6.75-7.13 13.1-12.4 m-vs7.86-8.26 11.25-10.7  m 8.64-9.04 10.23-9.78  m  9.51-10.09  9.3-8.77m-vs 10.62-11.23 8.33-7.88 w-m  13.4-14.22 6.61-6.23 w-m 14.76-15.55 6-5.7 w 17.63-18.37 5.03-4.83 m 19.17-19.91 4.63-4.46 w-m 19.64-20.564.52-4.32 m 20.18-21.05  4.4-4.22 w-m  20.7-21.57 4.29-4.12 w-m21.36-22.28 4.16-3.99 vs 22.17-23.6  4.01-3.77 m-s 24.12-25.23 3.69-3.53w  25.6-26.94 3.48-3.31 m 26.37-27.79 3.38-3.21 m 27.02-28.42  3.3-3.14m 27.53-28.89 3.24-3.09 m  28.7-30.09 3.11-2.97 m 29.18-30.72 3.06-2.91w-m 30.19-31.73 2.96-2.82 m 30.83-32.2   2.9-2.78 w 32.81-34.222.73-2.62 w 35.63-36.99 2.52-2.43 w 41.03-42.86  2.2-2.11 w 44.18-45.832.05-1.98 w 44.87-46.57 2.02-1.95 w 46.07-47.35 1.97-1.92 w 48.97-50.421.86-1.81 wand is thermally stable up to a temperature of at least 400° C.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot of the results for each experiment, where the y-axis isC₈ ring loss, and the x-axis is the ratio of the amount of para-xyleneto the amount of total xylene (PX:X). The “C₈ ring loss” is in units ofmol-% defined as (1−(C₈ naphthenes and aromatics in produce)/C₈naphthenes and aromatics in feed))*100.

FIG. 2 is a plot of wt-% A7, A9 and A10+ versus hours on stream for eachof the experiments demonstrating that the ring loss that is present inmostly transalkylation.

FIG. 3 shows the product distribution resulting from using catalyst #3and catalyst #5 of the examples.

FIG. 4 shows that the catalyst of the invention provides xylenes on thesame ortho-xylene versus para-xylene curve as MTW zeolite catalysts.

DETAILED DESCRIPTION OF THE INVENTION

Applicants have prepared an aluminosilicate zeolite which has beendesignated UZM-35 whose topological structure is related to MSE asdescribed in Atlas of Zeolite Framework Types, which is maintained bythe International Zeolite Association Structure Commission athttp://www.iza-structure.org/databases/. As is shown in U.S. applicationSer. No. 12/241,302 in detail, UZM-35 is different from MCM-68 in anumber of its characteristics. The instant microporous crystallinezeolite, UZM-35, has an empirical composition in the as-synthesized formand on an anhydrous basis expressed by the empirical formula:M_(m) ⁺R_(r) ⁺Al_((1-X))E_(x)Si_(y)O_(Z)where M represents a combination of potassium and sodium exchangeablecations. R is a singly charged organoammonium cation, examples of whichinclude but are not limited to the dimethyldipropylammonium cation(DMDPA⁺), dimethyldiisopropylammonium (DMDIP⁺), choline[(CH₃)₃N(CH₂)₂OH]⁺, ETMA⁺, DEDMA⁺, trimethylpropylammonium,trimethylbutylammonium, dimethyldiethanolammonium,methyltripropylammonium, TEA⁺, TPA⁺ and mixtures thereof and “r” is themole ratio of R to (Al+E) and varies from about 0.25 to about 2.0 while“m” is the mole ratio of M to (Al+E) and varies from about 0.05 to about3. The mole ratio of silicon to (Al+E) is represented by “y” whichvaries from about 2 to about 30. E is an element which is tetrahedrallycoordinated, is present in the framework and is selected from the groupconsisting of gallium, iron and boron. The mole fraction of E isrepresented by “x” and has a value from 0 to about 1.0, while “z” is themole ratio of O to (Al+E) and is given by the equation:z=(m·n+r+3+4·y)/2.Where M is only one metal, then the weighted average valence is thevalence of that one metal, i.e. +1 or +2. However, when more than one Mmetal is present, the total amount of:M_(m) ^(n+)=M_(m1) ^((n1)+)M_(m2) ^((n2)+)M_(m3) ^((n3)+)+ . . .and the weighted average valence “n” is given by the equation:

$n = \frac{{m_{1} \cdot n_{1}} + {m_{2} \cdot n_{2}} + {m_{3} \cdot n_{3}} + \ldots}{m_{1} + m_{2} + m_{3} + \ldots}$

The microporous crystalline zeolite, UZM-35, is prepared by ahydrothermal crystallization of a reaction mixture prepared by combiningreactive sources of M, R, aluminum, silicon and optionally E. Thesources of aluminum include but are not limited to aluminum alkoxides,precipitated aluminas, aluminum metal, aluminum salts and alumina sols.Specific examples of aluminum alkoxides include, but are not limited toaluminum ortho sec-butoxide and aluminum ortho isopropoxide. Sources ofsilica include but are not limited to tetraethylorthosilicate, colloidalsilica, precipitated silica and alkali silicates. Sources of the Eelements include but are not limited to alkali borates, boric acid,precipitated gallium oxyhydroxide, gallium sulfate, ferric sulfate, andferric chloride. Sources of the M metals, potassium and sodium, includethe halide salts, nitrate salts, acetate salts, and hydroxides of therespective alkali metals. R is an organoammonium cation selected fromthe group consisting of dimethyldipropylammonium, choline, ETMA, DEDMA,TEA, TPA, trimethylpropylammonium, trimethylbutylammonium,dimethyldiethanolammonium and mixtures thereof, and the sources includethe hydroxide, chloride, bromide, iodide and fluoride compounds.Specific examples include without limitation dimethyldipropylammoniumhydroxide, dimethyldipropylammonium chloride, dimethyldipropylammoniumbromide, dimethyldiisopropylammonium hydroxide,dimethyldiisopropylammonium chloride, dimethyldiisopropylammoniumbromide, ethyltrimethylammonium hydroxide, diethyldimethylammoniumhydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide,and tetrapropylammonium chloride.

Note that during synthesis, the metal M is +1 valance, specificallypotassium and sodium. However, in an alternative embodiment, thecomposition may undergo additional ion exchange steps post synthesis toprovide a material with one or more metals, M, having a +2 valance.

The reaction mixture containing reactive sources of the desiredcomponents can be described in terms of molar ratios of the oxides bythe formula:aM₂O:bR_(2/p)O:1-cAl₂O₃ :cE₂O₃ :dSiO₂ :eH₂Owhere “a” varies from about 0.05 to about 1.25, “b” varies from about1.5 to about 40, “c” varies from 0 to 1.0, “d” varies from about 4 toabout 40, “e” varies from about 25 to about 4000, and “p” is theweighted average valence of R and varies from 1 to about 2. If alkoxidesare used, it is preferred to include a distillation or evaporative stepto remove the alcohol hydrolysis products. The reaction mixture is nowreacted at a temperature of about 150° C. to about 200° C., about 165°C. to about 185° C., or about 170° C. to about 180° C., for a period ofabout 1 day to about 3 weeks and preferably for a time of about 5 daysto about 12 days in a sealed reaction vessel under autogenous pressure.After crystallization is complete, the solid product is isolated fromthe heterogeneous mixture by means such as filtration or centrifugation,and then washed with deionized water and dried in air at ambienttemperature up to about 100° C. It should be pointed out that UZM-35seeds can optionally be added to the reaction mixture in order toaccelerate the formation of the zeolite.

A preferred synthetic approach to make UZM-35 utilizes the chargedensity mismatch concept, which is disclosed in U.S. Pat. No. 7,578,993and Studies in Surface Science and Catalysis, (2004), Vol. 154A,364-372. The method disclosed in U.S. Pat. No. 7,578,993 employsquaternary ammonium hydroxides to solubilize aluminosilicate species,while crystallization inducing agents such as alkali and alkaline earthmetals and more highly charged organoammonium cations are oftenintroduced in a separate step. Once some UZM-35 seeds have beengenerated using this approach, the seeds can be used in a single stepsynthesis of UZM-35, using, for example, a combination ofdimethyldipropylammonium hydroxide and the alkali cations. The use ofcommercially available dimethyldipropylammonium hydroxide to prepareUZM-35 offers a great economic advantage over the structure directingagents previously employed(N,N,N′,N′-tetraalkylbicyclo[2.2.2]oct-7-ene-2R,3S:5R,6S-dipyrrolidiniumdication,N,N,N′,N′-tetraalkylbicyclo[2.2.2]octane-2R,3S:5R,6S-dipyrrolidiniumdication, and 1,1-dimethyl-4-cyclohexylpiperazinium cation) to preparealuminosilicates with the MSE topology. Additionally, dimethyldipropylammonium hydroxide can be employed as the hydroxide or the chloride inconcert with other inexpensive organoammonium hydroxides using thecharge density mismatch concept to reduce costs even further.

The UZM-35 aluminosilicate zeolite, which is obtained from theabove-described process, is characterized by the x-ray diffractionpattern, having at least the d-spacings and relative intensities setforth in Table A below.

TABLE A 2θ d (Å) I/Io % 6.45-6.8  13.7-13  m 6.75-7.13 13.1-12.4 m-vs7.86-8.26 11.25-10.7  m 8.64-9.04 10.23-9.78  m  9.51-10.09  9.3-8.77m-vs 10.62-11.23 8.33-7.88 w-m  13.4-14.22 6.61-6.23 w-m 14.76-15.55 6-5.7 w 17.63-18.37 5.03-4.83 w 19.17-19.91 4.63-4.46 w-m 19.64-20.564.52-4.32 m 20.18-21.05  4.4-4.22 w-m  20.7-21.57 4.29-4.12 w-m21.36-22.28 4.16-3.99 vs 22.17-23.6  4.01-3.77 m-s 24.12-25.23 3.69-3.53w  25.6-26.94 3.48-3.31 m 26.37-27.79 3.38-3.21 m 27.02-28.42  3.3-3.14m 27.53-28.89 3.24-3.09 m  28.7-30.09 3.11-2.97 m 29.18-30.72 3.06-2.91w-m 30.19-31.73 2.96-2.82 m 30.83-32.2   2.9-2.78 w 32.81-34.222.73-2.62 w 35.63-36.99 2.52-2.43 w 41.03-42.86  2.2-2.11 w 44.18-45.832.05-1.98 w 44.87-46.57 2.02-1.95 w 46.07-47.35 1.97-1.92 w 48.97-50.421.86-1.81 wAs will be shown in detail in the examples, the UZM-35 material isthermally and catalytically stable up to a temperature of at least 400°C. and in another embodiment, up to about 600° C.

One advantage of the UZM-35 material is that it may be used as a xyleneand ethylbenzene isomerization catalyst without having to remove thepotassium from the as synthesized material. In other words, thepotassium does not need to be removed in order for the isomerizationcatalyst to be active. The catalyst, in its catalytically active state,may contain molar ratios of potassium to aluminum of less than 0.90.

As synthesized, the UZM-35 material will contain some of theexchangeable or charge balancing cations in its pores. Theseexchangeable cations can be exchanged for other cations, or in the caseof organic cations, they can be removed by heating under controlledconditions. Because UZM-35 is a large pore zeolite, it is also possibleto remove some organic cations directly by ion exchange. The UZM-35zeolite may be modified in many ways to tailor it for use in aparticular application. Modifications include calcination, ion-exchange,steaming, various acid extractions, ammonium hexafluorosilicatetreatment, or any combination thereof, as outlined for the case ofUZM-4M in U.S. Pat. No. 6,776,975 B1 which is incorporated by referencein its entirety. Properties that are modified include porosity,adsorption, Si/Al ratio, acidity, thermal stability, and the like.

The UZM-35 compositions which are modified by one or more techniquesdescribed in the '975 patent (herein UZM-35HS) are described by theempirical formula on an anhydrous basis of:M1_(a) ^(n+)Al_((1-x))E_(x)Si_(y′)O_(z′)where M1 is at least one exchangeable cation selected from the groupconsisting of alkali, alkaline earth metals, rare earth metals, ammoniumion, hydrogen ion and mixtures thereof, “a” is the mole ratio of M1 to(Al+E) and varies from about 0.05 to about 50, “n” is the weightedaverage valence of M1 and has a value of about +1 to about +3, E is anelement selected from the group consisting of gallium, iron, boron, andmixtures thereof, “x” is the mole fraction of E and varies from 0 to1.0, y′ is the mole ratio of Si to (Al+E) and varies from greater thanabout 4 to virtually pure silica and z′ is the mole ratio of O to (Al+E)and has a value determined by the equation:z′=(a·n+3+4·y′)/2By virtually pure silica is meant that virtually all the aluminum and/orthe E metals have been removed from the framework. It is well known thatit is virtually impossible to remove all the aluminum and/or E metal.Numerically, a zeolite is virtually pure silica when y′ has a value ofat least 3,000, preferably 10,000 and most preferably 20,000. Thus,ranges for y′ are from 4 to 3,000 preferably greater than 10 to about3,000; 4 to 10,000 preferably greater than 10 to about 10,000 and 4 to20,000 preferably greater than 10 to about 20,000.

The UZM-35 as synthesized or as modified may be in a compositioncomprising the USM-35 as synthesized or as modified, a MFI topologyzeolite and an ERI topology zeolite. Typically, the amount of UZM-35 assynthesized or as modified in the composition will vary from about 55 wt% to about 75 wt. % or from about 55 wt-% to about 90 wt.-%. The amountof MFI zeolite varies from about 20 wt-% to about 35 wt-% of thecomposition or from about 10 wt-% to about 35 wt.-%, and the amount ofERI zeolite varies from about 3 wt-% to about 9 wt-% of the compositionor from about 3 wt-% to about 10 wt.-%. Of course, the sum of the amountof the three zeolites, absent any other impurities, adds up to 100 wt %of the composition.

The zeolite preferably is mixed with a binder for convenient formationof catalyst particles in a proportion of about 1 to 100 mass % zeoliteand 0 to 99 mass-% binder, with the zeolite preferably comprising fromabout 2 to 90 mass-% of the composite. The binder should preferably beporous, have a surface area of about 5 to about 800 m²/g, and relativelyrefractory to the conditions utilized in the hydrocarbon conversionprocess. Non-limiting examples of binders are aluminas, titania,zirconia, zinc oxide, magnesia, boria, silica-alumina, silica-magnesia,chromia-alumina, alumina-boria, silica-zirconia, silica, silica gel, andclays. Preferred binders are amorphous silica and alumina, includinggamma-, eta-, and theta-alumina, with gamma- and eta-alumina beingespecially preferred.

The zeolite with or without a binder can be formed into various shapessuch as pills, pellets, extrudates, spheres, etc. Preferred shapes areextrudates and spheres. Extrudates are prepared by conventional meanswhich involves mixing of zeolite either before or after adding metalliccomponents, with the binder and a suitable peptizing agent to form ahomogeneous dough or thick paste having the correct moisture content toallow for the formation of extrudates with acceptable integrity towithstand direct calcination. The dough then is extruded through a dieto give the shaped extrudate. A multitude of different extrudate shapesare possible, including, but not limited to, cylinders, cloverleaf,dumbbell and symmetrical and asymmetrical polylobates. It is also withinthe scope of this invention that the extrudates may be further shaped toany desired form, such as spheres, by any means known to the art.

Spheres can be prepared by the well known oil-drop method which isdescribed in U.S. Pat. No. 2,620,314 which is incorporated by reference.The method involves dropping a mixture of zeolite, and for example,alumina sol, and gelling agent into an oil bath maintained at elevatedtemperatures. The droplets of the mixture remain in the oil bath untilthey set and form hydrogel spheres. The spheres are then continuouslywithdrawn from the oil bath and typically subjected to specific agingtreatments in oil and an ammoniacal solution to further improve theirphysical characteristics. The resulting aged and gelled particles arethen washed and dried at a relatively low temperature of about 50-200°C. and subjected to a calcination procedure at a temperature of about450-700° C. for a period of about 1 to about 20 hours. This treatmenteffects conversion of the hydrogel to the corresponding alumina matrix.

Catalysts of the invention comprise a hydrogenation catalyst component,which is a platinum-group metal, including one or more of platinum,palladium, rhodium, ruthenium, osmium, and iridium. The preferredplatinum-group metal is platinum. The platinum-group metal component mayexist within the final catalyst composite as a compound such as anoxide, sulfide, halide, oxysulfide, etc., or as an elemental metal or incombination with one or more other ingredients of the catalystcomposite. It is believed that the best results are obtained whensubstantially all the platinum-group metal component exists in a reducedstate. The platinum-group metal component generally comprises from about0.01 to about 5 mass-% and preferably from about 0.1 to about 2% of thefinal catalyst composite, calculated on an elemental basis.

The platinum-group metal component may be incorporated into the catalystcomposite in any suitable manner. One method of preparing the catalystinvolves the utilization of a water-soluble, decomposable compound of aplatinum-group metal to impregnate the calcined sieve/binder composite.Alternatively, a platinum-group metal compound may be added at the timeof compositing the zeolite and binder. Yet another method of effecting asuitable metal distribution is by compositing the metal component withthe binder prior to co-extruding the zeolite and binder. Complexes ofplatinum-group metals which may be employed according to the above orother known methods include chloroplatinic acid, chloropalladic acid,ammonium chloroplatinate, bromoplatinic acid, platinum trichloride,platinum tetrachloride hydrate, platinum dichlorocarbonyl dichloride,tetramine platinic chloride, dinitrodiaminoplatinum, sodiumtetranitroplatinate (II), palladium chloride, palladium nitrate,palladium sulfate, diamminepalladium (II) hydroxide, tetramminepalladium(II) chloride, and the like.

It is within the scope of the present invention that the catalystcomposite may contain other metal components known to modify the effectof the platinum-group metal component. Such metal modifiers may includerhenium, tin, germanium, lead, cobalt, nickel, indium, gallium, zinc,uranium, dysprosium, thallium, and mixtures thereof. Catalyticallyeffective amounts of such metal modifiers may be incorporated into thecatalyst by any means known in the art to effect a homogeneous orstratified distribution.

The catalyst composite of the present invention may contain a halogencomponent. The halogen component may be either fluorine, chlorine,bromine or iodine or mixtures thereof, with chlorine being preferred.The halogen component is generally present in a combined state with theinorganic-oxide support. The optional halogen component is preferablywell dispersed throughout the catalyst and may comprise from more than0.2 to about 5 wt. %, calculated on an elemental basis, of the finalcatalyst. The halogen component may be incorporated in the catalystcomposite in any suitable manner, either during the preparation of theinorganic-oxide support or before, while or after other catalyticcomponents are incorporated.

The catalyst composite is dried at a temperature of from about 100° toabout 320° C. for a period of from about 2 to about 24 or more hoursand, usually, calcined at a temperature of from 400° to about 650° C. inan air atmosphere for a period of from about 1 to about 10 hours untilthe metallic compounds present are converted substantially to the oxideform. If desired, the optional halogen component may be adjusted byincluding a halogen or halogen-containing compound in the airatmosphere.

The resultant calcined composite optimally is subjected to asubstantially water-free reduction step to insure a uniform and finelydivided dispersion of the optional metallic components. The reductionoptionally may be effected in situ. Substantially pure and dry hydrogen(i.e., less than 20 vol. ppm H₂O) preferably is used as the reducingagent in this step. The reducing agent contacts the catalyst atconditions, including a temperature of from about 200° to about 650° C.and for a period of from about 0.5 to about 10 hours, effective toreduce substantially all of the Group VIII metal component to themetallic state. In some cases the resulting reduced catalyst compositemay also be beneficially subjected to presulfiding by a method known inthe art to incorporate in the catalyst composite from about 0.05 toabout 1.0 mass-% sulfur calculated on an elemental basis.

The feedstock to aromatics isomerization comprises isomerizablealkylaromatic hydrocarbons of the general formula C₆H_((6-n))R_(n),where n is an integer from 1 to 5 and R is CH₃, C₂H₅, C₃H₇, or C₄H₉, inany combination and including all the isomers thereof to obtain morevaluable isomers of the alkylaromatic. Suitable alkylaromatichydrocarbons include without limitation ortho-xylene, meta-xylene,para-xylene, ethylbenzene, ethyltoluenes, tri-methylbenzenes,di-ethylbenzenes, tri-ethyl-benzenes, methylpropylbenzenes,ethylpropylbenzenes, di-isopropylbenzenes, and mixtures thereof.

Isomerization of a C₈-aromatic mixture containing ethylbenzene andxylenes is a particularly preferred application for the zeolites of theinvention. Generally such mixture will have an ethylbenzene content inthe approximate range of 5 to 50 mass-%, an ortho-xylene content in theapproximate range of 0 to 35 mass-%, a meta-xylene content in theapproximate range of 20 to 95 mass-% and a para-xylene content in theapproximate range of 0 to 15 mass-%. It is preferred that theaforementioned C₈ aromatics comprise a non-equilibrium mixture, i.e., atleast one C₈-aromatic isomer is present in a concentration that differssubstantially (defined herein as a difference of at least 5 mass-% ofthe total C₈ aromatics) from the thermodynamic equilibrium concentrationof that isomer at isomerization conditions. Usually the non-equilibriummixture is prepared by removal of para- and/or ortho-xylene from a freshC₈ aromatic mixture obtained from an aromatics-production process, andpreferably the non-equilibrium mixture contains less than 5 mass-%para-xylene.

The alkylaromatic hydrocarbons may be utilized in the present inventionas found in appropriate fractions from various refinery petroleumstreams, e.g., as individual components or as certain boiling-rangefractions obtained by the selective fractionation and distillation ofcatalytically cracked or reformed hydrocarbons. The isomerizablearomatic hydrocarbons need not be concentrated; the process of thisinvention allows the isomerization of alkylaromatic-containing streamssuch as catalytic reformate with or without subsequent aromaticsextraction to produce specified xylene isomers and particularly toproduce para-xylene. A C₈-aromatics feed to the present process maycontain nonaromatic hydrocarbons, i.e., naphthenes and paraffins, in anamount up to 30 mass-%. Preferably the isomerizable hydrocarbons consistessentially of aromatics, however, to ensure pure products fromdownstream recovery processes.

According to the process of the present invention, an alkylaromatichydrocarbon feed mixture, preferably in admixture with hydrogen, iscontacted with a UZM-35 containing catalyst described herein in analkylaromatic hydrocarbon isomerization zone. Contacting may be effectedusing the catalyst in a fixed-bed system, a moving-bed system, afluidized-bed system, or in a batch-type operation. In a fixed-bedsystem, the danger of attrition loss of the valuable catalyst may beminimized and operation is simplified. In this system, a hydrogen-richgas and the feed mixture are preheated by suitable heating means to thedesired reaction temperature and then passed into an isomerization zonecontaining a fixed bed of catalyst. The conversion zone may be one ormore separate reactors with suitable means therebetween to ensure thatthe desired isomerization temperature is maintained at the entrance toeach zone. The reactants may be contacted with the catalyst bed ineither upward-, downward-, or radial-flow fashion, and the reactants maybe in the liquid phase, a mixed liquid-vapor phase, or a vapor phasewhen contacted with the catalyst.

The alkylaromatic feed mixture, preferably a non-equilibrium mixture ofC₈ aromatics, is contacted with the isomerization catalyst at suitablealkylaromatic-isomerization conditions. Such conditions comprise atemperature ranging from about 0° to 600° C. or more, with a specificembodiment in the range of from about 100° to 500° C. The pressuregenerally is from about 10 kPa to about 5 MPa absolute, with oneembodiment being less than about 5 MPa absolute. Sufficient catalyst iscontained in the isomerization zone to provide a liquid hourly spacevelocity with respect to the hydrocarbon feed mixture of from about 0.1to 30 hr⁻¹, with a specific embodiment of 0.5 to 10 hr⁻¹. Thehydrocarbon feed mixture optimally is reacted in admixture with hydrogenat a hydrogen/hydrocarbon mole ratio of about 0.5:1 to about 10:1 ormore. Other inert diluents such as nitrogen, argon and lighthydrocarbons may be present.

The reaction proceeds via the mechanism of isomerizing xylenes whilereacting ethylbenzene to form a xylene mixture via conversion to andreconversion from naphthenes. The yield of xylenes in the product thusis enhanced by forming xylenes from ethylbenzene. The loss of C₈aromatics through the reaction thus is desirably low.

The particular scheme employed to recover an isomerized product from theeffluent of the reactors of the isomerization zone is not deemed to becritical to the instant invention, and any effective recovery schemeknown in the art may be used. Typically, the reactor effluent will becondensed and the hydrogen and light-hydrocarbon components removed byflash separation. The condensed liquid product then is fractionated toremove light and/or heavy byproducts and obtain the isomerized product.In some instances, certain product species such as ortho-xylene may berecovered from the isomerized product by selective fractionation. Theproduct from isomerization of C₈ aromatics usually is processed toselectively recover the para-xylene isomer, optionally bycrystallization. Selective adsorption is preferred using crystallinealuminosilicates according to U.S. Pat. No. 3,201,491. Improvements andalternatives within the preferred adsorption recovery process aredescribed in U.S. Pat. Nos. 3,626,020, 3,696,107, 4,039,599, 4,184,943,4,381,419 and 4,402,832, each incorporated herein by reference.

In a separation/isomerization process combination relating to theprocessing of an ethylbenzene/xylene mixture, a fresh C₈-aromatics feedis combined with isomerized product comprising C₈ aromatics andnaphthenes from the isomerization reaction zone and fed to a para-xyleneseparation zone; the para-xylene-depleted stream comprising anon-equilibrium mixture of C₈ aromatics is fed to the isomerizationreaction zone, where the C₈-aromatic isomers are isomerized tonear-equilibrium levels to obtain the isomerized product. In thisprocess scheme non-recovered C₈-aromatic isomers preferably are recycledto extinction until they are either converted to para-xylene or lost dueto side-reactions. Ortho-xylene separation, preferably by fractionation,also may be effected on the fresh C₈-aromatic feed or isomerizedproduct, or both in combination, prior to para-xylene separation.

The following examples are presented in illustration of this inventionand are not intended as undue limitations on the generally broad scopeof the invention as set out in the appended claims.

The structure of the UZM-35 zeolite of this invention was determined byx-ray analysis. The x-ray patterns presented in the following exampleswere obtained using standard x-ray powder diffraction techniques. Theradiation source was a high-intensity, x-ray tube operated at 45 kV and35 ma. The diffraction pattern from the copper K-alpha radiation wasobtained by appropriate computer based techniques. Flat compressedpowder samples were continuously scanned at 2° to 56° (2θ). Interplanarspacings (d) in Angstrom units were obtained from the position of thediffraction peaks expressed as θ where θ is the Bragg angle as observedfrom digitized data. Intensities were determined from the integratedarea of diffraction peaks after subtracting background, “I_(o)” beingthe intensity of the strongest line or peak, and “I” being the intensityof each of the other peaks.

As will be understood by those skilled in the art the determination ofthe parameter 2θ is subject to both human and mechanical error, which incombination can impose an uncertainty of about ±0.4° on each reportedvalue of 2θ. This uncertainty is, of course, also manifested in thereported values of the d-spacings, which are calculated from the 2θvalues. This imprecision is general throughout the art and is notsufficient to preclude the differentiation of the present crystallinematerials from each other and from the compositions of the prior art. Insome of the x-ray patterns reported, the relative intensities of thed-spacings are indicated by the notations vs, s, m, and w whichrepresent very strong, strong, medium, and weak, respectively. In termsof 100×I/I_(o), the above designations are defined as:w=0-15;m=15-60:s=60-80 and vs=80-100

In certain instances the purity of a synthesized product may be assessedwith reference to its x-ray powder diffraction pattern. Thus, forexample, if a sample is stated to be pure, it is intended only that thex-ray pattern of the sample is free of lines attributable to crystallineimpurities, not that there are no amorphous materials present.

In order to more fully illustrate the invention, the following examplesare set forth. It is to be understood that the examples are only by wayof illustration and are not intended as an undue limitation on the broadscope of the invention as set forth in the appended claims.

EXAMPLE 1

An aluminosilicate reaction solution was prepared by first mixing 27.17g of aluminum hydroxide (27.78 mass-% Al) and 1053.58 gdimethyldipropylammonium hydroxide (18.8 mass-% solution), whilestirring vigorously. After thorough mixing, 505.96 g Ludox™ AS-40 (40mass-% SiO₂) was added. The reaction mixture was homogenized for anadditional hour with a high speed mechanical stirrer, sealed in a Teflonbottle, and placed in an oven overnight at 100° C. Analysis showed thealuminosilicate solution contained 6.16 wt. % Si and 0.67 wt. % Al(Si/Al molar ratio of 8.83).

A 1200 g portion of the above aluminosilicate solution was continuouslystirred. A composite aqueous solution containing 28.56 g of KOH and 3.6g of NaOH dissolved in 150 g distilled water, was added, drop-wise, tothe aluminosilicate solution. After the addition was completed, theresulting reaction mixture was homogenized for 1 hour, transferred to a2000 ml Parr stainless steel autoclave which was heated to 175° C. andmaintained at that temperature for 216 hrs.

The solid product was recovered by centrifugation, washed withde-ionized water and dried at 95° C. to 100° C. The product wasidentified as UZM-35 by xrd. Representative diffraction lines observedfor the product are shown in Table 1. The product composition wasdetermined by elemental analysis to consist of the following moleratios: Si/Al=7.92, Na/Al=0.1, K/Al=0.48.

TABLE 1 2θ d (Å) I/I₀ % 6.65 13.26 m 6.95 12.69 m 8.10 10.90 m 8.87 9.95m 9.76 9.05 m 10.83 8.13 w 13.76 6.43 w 15.22 5.81 w 18.00 4.92 w 19.464.55 m 19.62 4.52 m 20.06 4.42 m 20.63 4.3 m 21.1 4.20 m 21.76 4.08 vs21.92 4.05 m 22.07 4.03 m 22.55 3.93 m 22.73 3.90 m 23.08 3.85 s 23.423.79 m 23.51 3.77 m 24.04 3.69 m 24.53 3.62 w 25.9 3.43 m 25.99 3.42 w26.27 3.38 m 26.92 3.3 m 27.57 3.23 m 27.76 3.21 m 28.17 3.16 m 28.863.09 w 29.27 3.04 m 29.72 3.00 w 30.26 2.95 w 30.91 2.88 m 31.38 2.84 w33.61 2.68 w 34.65 2.58 w 35.43 2.53 w 36.18 2.48 w 41.77 2.16 w 44.72.02 w 45.32 1.99 w 45.63 1.98 w 46.55 1.94 w 47.62 1.90 w 47.94 1.89 w49.70 1.83 w 51.06 1.78 w

EXAMPLE 2

The UZM-35 of Example 1 was calcined at 570° C. for 7 hours undernitrogen and then under air. The UZM-35 was then ammonium ion exchangedto exchange Na⁺ or K⁺ cations for NH₄ ⁺. The UZM-35 was ammoniumion-exchanged by contacting 500 mL of 1 M NH₄NHO₃ solution with 40 gUZM-35 at 80° C. and stirring for 1 hour, filtered and washed. Theprocedure was repeated three times. The ion-exchanged UZM-35 was thencalcined at 550° C. in air for 2 h to convert NH₄ ⁺ to H⁺ by loss ofammonia.

EXAMPLE 3

Alternatively, the ammonium exchange was performed first and thenfollowed by calcination to remove the template and exchange Na⁺ or K⁺cations for NH₄ ⁺. The UZM-35 of Example 1 was ammonium ion exchanged bycontacting 1000 mL of 1 M NH₄NO₃ solution with 100 g UZM-35 at 80° C.and stirring for 2 hours. The ion-exchanged UZM-35 was then calcined at560° C. for 7 hours under nitrogen and then air. A second ion-exchangewas carried out by contacting 1000 mL of 1 M NH₄NO₃ solution with 95 gUZM-35 at 80° C. and stirring for 1 hour. The ion-exchanged UZM-35 wasfiltered and dried.

EXAMPLE 4

The UZM-35 of Example 3 was then steamed at 600° C. for 2 h in avertical steamer by passing an air stream containing 50 vol-% steam overthe UZM-35. The steamed UZM-35 was ion-exchanged with the NH₄NO₃solution again. The resulting steam-ammonium UZM-35 was extruded at70/30 ratio with alumina. The extrudates were calcined at 550° C. in airfor 2 hours to convert NH₄ ⁺ to H⁺ by loss of ammonia.

COMPARATIVE EXAMPLE 5

Three different catalysts were compared with an embodiment of theclaimed catalyst for performance in xylene isomerization. The first andsecond catalysts were extrudates made with 20 Si/Al ratio MTW zeolitepowder made according to the method described in U.S. Pat. No. 7,525,008and V-251 alumina (available from UOP, LLC.). The first catalyst had a20 weight-% zeolite concentration, while the second catalyst had a 50weight-% zeolite concentration, based on the weight of the extrudate.

The third and fourth catalysts were made with 20 Si/Al ratio MTW zeoliteand both had 80 wt.-% zeolite concentrations based on the catalyticcomposite, with an alumina binder. The third catalyst was an oil-droppedsphere and the fourth catalyst was an extrudate which had been ionexchanged with ammonium nitrate, washed, and calcined.

The embodiment of the invention tested as the fifth catalyst was asteamed 70 weight-% UZM-35 zeolite extrudate having an alumina binder.

In each experiment, about 2 grams of catalyst was loaded into a fixedbed reactor. Feed and hydrogen were introduced to the reactor to contactthe catalyst. The feed was a mixture of 56 weight-% meta-xylene, 22weight-% ortho-xylene, 1 weight-% para-xylene, 1 weight-% toluene, and 6weight-% C8 naphthenes with the balance ethylbenzene. The feed waspumped at 10 WHSV, and the H₂/HC ratio was 4. The reactor was operatedat about 786 kPa absolute and each catalyst was tested at temperatures365° C., 375° C. and 385° C. The effluent of the reactor was monitoredusing gas chromatography. For each experiment, the results were plottedas shown in FIG. 1 where the y-axis is C₈ ring loss, and the x-axis isthe ratio of the amount of para-xylene to the amount of total xylene(PX:X). The “C₈ ring loss” is in units of mol-% defined as (1−(C₈naphthenes and aromatics in produce)/C₈ naphthenes and aromatics infeed))*100.

As FIG. 1 shows, the embodiment of the invention demonstrated aninteresting trend with time on stream. The selectivity of the catalystof the invention improves early in the run without significant loss ofxylene isomerization activity, thereby providing an initial reduction inbyproducts. Also, the catalyst of the invention provided an advantage inlower ring loss as compared to the oil dropped sphere of 80-wt. % MTWwith alumina binder. The ring loss that is present is mostlytransalkylation, see FIG. 2 where the comparison of Catalyst #5 toCatalyst #3 shows its lower ring loss at equivalent P—X/X. The catalystof the invention has a different product distribution than MTW zeolite,resulting in a different distribution, see FIG. 3, which shows theproduct distribution in weight-percent at P—X/X of 22.9 weight-%.Consistent with MTW zeolite, there is no restriction of ortho-xylene,see FIG. 4 which shows that the catalyst of the invention providesxylenes on the same ortho-xylene versus para-xylene curve as MTWzeolite.

COMPARATIVE EXAMPLE 6

Three different catalysts were compared with an embodiment of theclaimed catalyst for performance in xylene transalkylation. The firstcatalyst was an extrudate of UZM-35 zeolite powder and V-251 aluminawhere the first catalyst has a 70 weight-% zeolite concentration basedon the finished extrudate. The second catalyst was an extrudate of a 2.2wt. % Ga and 0.6 wt. % Al on MFI zeolite with V-251 alumina binder inaccordance with the teachings of U.S. Pat. No. 4,957,891. The secondcatalyst had a 50 weight-% zeolite concentration, based on the weight ofthe extrudate. The third catalyst was an ammonium nitrate-exchanged,steamed oil-dropped sphere of 65 weight percent MFI and analuminophosphate binder prepared using the method of Example 1 of U.S.Pat. No. 6,143,941.

In each experiment, about 1 gram of catalyst was loaded into a fixed bedreactor. Feed and hydrogen were introduced to the reactor to contact thecatalyst. The feed was a mixture of 60 weight-% meta-xylene, 25 weight-%ortho-xylene, 15 weight-% ethylbenzene. The feed was pumped at 10 WHSVbased on the amount of zeolite, and the H₂/HC ratio was 4. The reactorwas operated at about 786 kPa absolute and each catalyst was tested attemperatures 375° C., 385° C. and 395° C. The catalysts were introducedas a physical mixture with 0.4 grams of 14/20 meshed 0.3 weight-%platinum on alumina catalyst modified with 0.6 weight-% indium and 0.3weight-% tin in accordance with Example III in U.S. Pat. No. 6,048,449.

The effluent of the reactor was monitored using gas chromatography. Foreach experiment, the results are shown in Table 2. From Table 2 it canbe seen that the conversion of ethylbenzene is relatively low comparedto the MFI zeolite structure. Much of the conversion is ethyl transferto other aromatics. The xylene isomerization activity is high as shownby the ratio of para-xylene to total xylenes, and is close toequilibrium.

TABLE 2 To Achieve 60% ethylbenzene conversion Catalyst #1 Catalyst #2Catalyst #3 Temp ° C. 396 375 365 Net wt % toluene 8.1 2.8 2.5 andtrimethyl-benzenes. Para-xylene:Xylene ratio 0.239 0.241 0.230

The invention claimed is:
 1. A process for isomerizing a non-equilibriumfeed mixture comprising xylenes and ethylbenzene comprising contactingthe feed mixture in the presence of hydrogen in an isomerization zonewith a catalyst at isomerization conditions and producing an isomerizedproduct comprising a higher proportion of p-xylene than in the feedmixture, wherein the catalyst comprises a UZM-35HS microporouscrystalline zeolite and a hydrogenation component, wherein the UZM-35HShas a three-dimensional framework of at least AlO₂ and SiO₂ tetrahedralunits and an empirical composition on an anhydrous basis expressed by anempirical formula of:M1_(a) ^(n+)Al_((1-x))E_(x)Si_(y′)O_(z′) where M1 is at least oneexchangeable cation selected from the group consisting of alkali,alkaline earth metals, rare earth metals, ammonium ion, hydrogen ion andmixtures thereof, “a” is the mole ratio of M1 to (Al+E) and varies fromabout 0.05 to about 50, “n” is the weighted average valence of M1 andhas a value of about +1 to about +3, E is an element selected from thegroup consisting of gallium, iron, boron, and mixtures thereof, “x” isthe mole fraction of E and varies from 0 to 1.0, y′ is the mole ratio ofSi to (Al+E) and varies from greater than about 4 to virtually puresilica and z′ is the mole ratio of O to (Al+E) and has a valuedetermined by the equation:z′=(a·n+3+4·y′)/2 and is characterized in that it has the x-raydiffraction pattern having at least the d-spacings and intensities setforth in Table A: TABLE A 2θ d (Å) I/Io % 6.45-6.8  13.7-13  m 6.75-7.1313.1-12.4 m-vs 7.86-8.26 11.25-10.7  m 8.64-9.04 10.23-9.78  m 9.51-10.09  9.3-8.77 m-vs 10.62-11.23 8.33-7.88 w-m  13.4-14.226.61-6.23 w-m 14.76-15.55  6-5.7 w 17.63-18.37 5.03-4.83 m 19.17-19.914.63-4.46 w-m 19.64-20.56 4.52-4.32 m 20.18-21.05  4.4-4.22 w-m 20.7-21.57 4.29-4.12 w-m 21.36-22.28 4.16-3.99 vs 22.17-23.6  4.01-3.77m-s 24.12-25.23 3.69-3.53 w  25.6-26.94 3.48-3.31 m 26.37-27.793.38-3.21 m 27.02-28.42  3.3-3.14 m 27.53-28.89 3.24-3.09 m  28.7-30.093.11-2.97 m 29.18-30.72 3.06-2.91 w-m 30.19-31.73 2.96-2.82 m30.83-32.2   2.9-2.78 w 32.81-34.22 2.73-2.62 w 35.63-36.99 2.52-2.43 w41.03-42.86  2.2-2.11 w 44.18-45.83 2.05-1.98 w 44.87-46.57 2.02-1.95 w46.07-47.35 1.97-1.92 w 48.97-50.42 1.86-1.81 w

and is thermally stable up to a temperature of at least 400° C.
 2. Theprocess of claim 1 further comprising recovery of ortho-xylene from oneor both of the isomerized product and fresh feed mixture.
 3. The processof claim 1 further comprising recovery of para-xylene from one or bothof the isomerized product and fresh feed mixture.
 4. The process ofclaim 1 where the isomerization conditions include a temperature ofabout 100° C. to about 500° C., a pressure from about 10 kPa absolute toabout 5 MPa absolute atmospheres and a liquid hourly spare velocity ofabout 0.5 to about 10 hr⁻¹.
 5. The process of claim 1 where the hydrogenis present at a hydrogen to hydrocarbon ratio of about 0.5:1 to about10:1.
 6. The process of claim 1 wherein “x” of the UZM-35 zeolite iszero.
 7. The process of claim 1 wherein between about 1 and about 60mass-% of the C₈ aromatics in the feed stream is ethylbenzene.
 8. Theprocess of claim 1 wherein the hydrogenation component comprisesplatinum group metal-containing component.
 9. The process of claim 8wherein the hydrogenation component comprises sulfided platinum.
 10. Theprocess of claim 1 wherein the catalyst further comprises a metalmodifier component or a halogen component.
 11. The process of claim 1wherein the UZM-35HS is in a composition comprising the USM-35HS, a MFItopology zeolite and an ERI topology zeolite.
 12. The process of claim11 wherein the amount of UZM-35HS in the composition ranges from about55 wt % to about 75 wt % of the composition, the amount of MFI topologyzeolite ranges from about 20 wt-% to about 35 wt-% of the composition,and the amount of ERI topology zeolite in the composition ranges fromabout 3 wt-% to about 9 wt-% of the composition.
 13. A process forisomerizing a non-equilibrium feed mixture comprising xylenes andethylbenzene comprising contacting the feed mixture in the presence ofhydrogen in an isomerization zone with a catalyst at isomerizationconditions and producing an isomerized product comprising a lowerproportion of ethylbenzene than in the feed mixture, wherein thecatalyst comprises a UZM-35HS microporous crystalline zeolite and ahydrogenation component, wherein the UZM-35HS has a three-dimensionalframework of at least AlO₂ and SiO₂ tetrahedral units and an empiricalcomposition on an anhydrous basis expressed by an empirical formula of:M1_(a) ^(n+)Al_((1-x))E_(x)Si_(y′)O_(z′) where M1 is at least oneexchangeable cation selected from the group consisting of alkali,alkaline earth metals, rare earth metals, ammonium ion, hydrogen ion andmixtures thereof, “a” is the mole ratio of M1 to (Al+E) and varies fromabout 0.05 to about 50, “n” is the weighted average valence of M1 andhas a value of about +1 to about +3, E is an element selected from thegroup consisting of gallium, iron, boron, and mixtures thereof, “x” isthe mole fraction of E and varies from 0 to 1.0, y′ is the mole ratio ofSi to (Al+E) and varies from greater than about 4 to virtually puresilica and z′ is the mole ratio of O to (Al+E) and has a valuedetermined by the equation:z′=(a·n+3+4·y′)/2 and is characterized in that it has the x-raydiffraction pattern having at least the d-spacings and intensities setforth in Table A: TABLE A 2θ d (Å) I/Io % 6.45-6.8  13.7-13  m 6.75-7.1313.1-12.4 m-vs 7.86-8.26 11.25-10.7  m 8.64-9.04 10.23-9.78  m 9.51-10.09  9.3-8.77 m-vs 10.62-11.23 8.33-7.88 w-m  13.4-14.226.61-6.23 w-m 14.76-15.55  6-5.7 w 17.63-18.37 5.03-4.83 w 19.17-19.914.63-4.46 w-m 19.64-20.56 4.52-4.32 m 20.18-21.05  4.4-4.22 w-m 20.7-21.570 4.29-4.12 w-m 21.36-22.28 4.16-3.99 vs 22.17-23.6 4.01-3.77 m-s 24.12-25.23 3.69-3.53 w  25.6-26.94 3.48-3.31 m26.37-27.79 3.38-3.21 m 27.02-28.42  3.3-3.14 m 27.53-28.89 3.24-3.09 m 28.7-30.09 3.11-2.97 m 29.18-30.72 3.06-2.91 w-m 30.19-31.73 2.96-2.82m 30.83-32.2   2.9-2.78 w 32.81-34.22 2.73-2.62 w 35.63-36.99 2.52-2.43w 41.03-42.86  2.2-2.11 w 44.18-45.83 2.05-1.98 w 44.87-46.57 2.02-1.95w 46.07-47.35 1.97-1.92 w 48.97-50.42 1.86-1.81 w

and is thermally stable up to a temperature of at least 400° C.
 14. Theprocess of claim 13 wherein “x” of the UZM-35 zeolite is zero.
 15. Theprocess of claim 13 where the isomerization conditions include atemperature of about 100° C. to about 500° C., a pressure from about 10kPa absolute to about 5 MPa absolute atmospheres and a liquid hourlyspare velocity of about 0.5 to about 10 hr⁻¹.
 16. The process of claim13 where the hydrogen is present at a hydrogen to hydrocarbon ratio ofabout 0.5:1 to about 10:1.
 17. The process of claim 13 wherein betweenabout 1 and about 60 mass-% of the C₈ aromatics in the feed stream isethylbenzene.
 18. The process of claim 13 wherein the hydrogenationcomponent comprises platinum group metal-containing component.
 19. Theprocess of claim 13 wherein the hydrogenation component comprisessulfided platinum.
 20. The process of claim 13 wherein the catalystfurther comprises a metal modifier component or a halogen component. 21.The process of claim 13 wherein the UZM-35HS is in a compositioncomprising the USM-35HS, a MFI topology zeolite and an ERI topologyzeolite.
 22. The process of claim 20 wherein the amount of UZM-35HS inthe composition ranges from about 55 wt % to about 75 wt % of thecomposition, the amount of MFI topology zeolite ranges from about 20wt-% to about 35 wt-% of the composition, and the amount of ERI topologyzeolite in the composition ranges from about 3 wt-% to about 9 wt-% ofthe composition.